Control system



June 13, 1957 F. A. DAHLMN ETAL CONTROL SYSTEM Filed June l1, 1965Frede/un il. Jmawf E am 2f. WW

United States Patent O 3,324,770 CONTROL SYSTEM Frederick A. Dahlman andFrederick L. .ianowsk both of Corning, NX., assignors to Corning GlassWorks, Corning, N Y., a corporation of New York Filed June 11, 1965,Ser. No. 463,257 7 Claims. (Cl. 91-40) The present invention relates toa control system and, more particularly, to a modification to apressurized fluid control system of a type old and well known in theart.

It is old and well known to provide a pressurized uid control system inwhich pressurized fiuid impulse signals are supplied by a timing orprograming device to a gating means, such as a iuid valve, for actuationthereof to selectively supply pressurized fluid to a fluid motor forreciprocating operation of a second mechanism between first and secondeXtreme positions in synchronism with a first mechanism controlling oralso being controlled by said programming device. However, it issometimes desirable that operation of said first mechanism be permittedto continue while said second mechanism is actuated to and stopped in aposition intermediate said extreme positions thereof as, for example,when repairs to such second `mechanism are necessary. It is accordinglyone object of the present invention to provide an arrangement of controlapparatus, in a type of control system such as that discussed, whichprovides for relatively rapid actuation of said second mechanism to anintermediate position in response to a control signal and the stoppingof such second mechanism in such intermediate position until the controlsignal is terminated.

Other objects and characteristic features of the invention will becomeapparent as the description proceeds.

In accomplishing the objects of the invention there is provided cammeans which indicate the position which said second mechanism occupiesat any point in time, and a plurality of gating means partiallycontrolled by said cam means and at times actuated in response to acontrol signal to provide for actuation of such second mechanism to saidintermediate position.

The invention will best be understood with reference to the singledrawing figure which comprises a schematic diagram of a control systemembodying the invention.

Referring to the drawing in detail, there is shown in block diagram forma first mechanism 10 which, as indicated in the conventional manner bythe dotted line 11, controls or is controlled by a timing or programmingdevice 12. The details of the mechanism 19 are not shown in the drawingsince such mechanism may be any type of machine or device well known inthe art and controlling or controlled by a programmer, such as 12.

Programmer 12 includes first and second cams 13 and 14 normallycontinuously rotating in a clockwise direction, as indicated by thearrows, thereon, and having cam lobes 16 and 17, respectively.Programmer 12 also includes first and second two-position pressurizedfluid control valves 18 and 19 having plunger assemblies 21 and 22,respectively. Valves 18 and 19 are normally in first positions in whichconductors or conduits 24 and 28 are respectively connected therethroughto fluid sinks and 28, respectively, or to atmosphere if the pressurizedfiuid employed is compressed air, for example. Whenever the plungerassembly of the respective valve 18 or 19 is depressed by the respectivecam lobe 15 or 17 during rotation of the cams 13 and 14, such valve isactuated to connect the respective conduit 24 or 28 to a conduit orconductor 23. Valves 18 and 19 are returned to their said normalpositions by springs or by fluid pressure following an actuation thereofby the respective cam lobes 16 or 17, and when they are no longerdepressed by their respecice tively associated cam lobes. Programmers ortiming devices such as 12, and valves such as 18 and 19 are well knownand no further detailed discussion thereof is believed necessary.Pressurized fluid from a source thereof is provided over said conductoror conduit 23 to said control valves 18 and 19. Such iiuid source is notshown in the drawings for purposes of simplification thereof; however,such pressurized fiuid may, for example, be compressed air.

When valve 18 is actuated to its on position, the pressurized fluidsupplied thereto from conductor or conduit 23 is permitted to flowthrough conductor or conduit 24 and through a restriction 26 to one endof a two-position, four-way gating means or valve 27. Similarly, whenvalve 19 is actuated to its on position, the pressurized fiuid suppliedthereto from conductor 23 is permitted to fiow through conductor orconduit 28 and through a restriction 2S to the other end of said gatinglmeans 27. As will be further discussed hereinafter in this description,gating means 27 alternates the fiow of pressurized fluid from a sourcethereof to conductors or conduits 29 and 31, and thence to first andsecond ends of a reciprocating pressurized fluid motor 32, in accordancewith said permitted ow of pressurized fiuid through conductors 24 and 28to said ends of gating means or valve 27. Gating means or valves, suchas 27, and reciprocating fluid pressure motors, such as 28, are wellknown and no further detailed discussion thereof is believed necessary.

Fluid pressure motor 32 includes the usual piston rod 33 which isconnected in any convenient manner to the previously mentioned secondmechanism, such second mechanism being shown as including a rack 34 anda pinion gear 36 each having gear teeth in cooperative inter- -meshingengagement, as in the usual arrangement of rack and pinion gears. Itwill be readily apparent that rack 34 and pinion gear 36 arereciprocatively actuated between first and second extreme positions inaccordance with the reciprocating actuation of piston rod 33 ofpressurized fluid motor 32.

The apparatus or control system thus far described is old and well knownand the apparatus hereinafter described is the inventive modification tosuch old apparatus, that is, the apparatus hereinafter described is thenew apparatus or the modification embodying the invention.

As indicated in the conventional manner by the dotted line 37, cam meanscomprising cam wheels 38 and 39 are connected to pinion gear 36 forcorresponding driven rotation of such wheels by such gear. That is, whenpinion gear 36 is driven by rack 34 in a clockwise direction, asindicated by the arrow, cam wheels 38 and 39 are correspondingly drivenin such direction, as indicated by the arrows on such wheels. Likewise,when gear 36 is driven in a counterclockwise direction by rack 34,wheels 38 and 39 are correspondingly driven in a counterclockwisedirection.

Associated with cam wheel 38 is a cam follower 41 having a roller 42pivotally mounted on one end thereof and bearing against the outerperiphery of cam wheel 38. The other end of cam follower 41 is connectedto a two-position, four-way gating means or valve 43 to be hereinafterdiscussed. Said outer periphery of cam 38 is provided with a recessedportion 48 which is located on such outer periphery so as to correspondto the previously-mentioned intermediate position of said secondmechanism, that is, of said rack and pinion gear 34-36. The location andpurpose of such recessed portion 48 will be further discussedhereinafter.

There is associated with cam wheel 39 a cam follower 44 having a roller46 pivotally mounted on one end thereof and bearing against the outerperiphery of cam wheel 39. The other end of cam follower 44 is connectedto a three-position three-way gating means or valve 47 to be hereinafterdiscussed. Said outer periphery of cam wheel 39 is provided with tworecessed portions, that is, two portions of lesser radii than theremainder of the wheel. A rst of such recessed portions is indicated bythe reference character 49 and extends about the outer periphery of camwheel 39 a distance slightly less than, but substantially correspondingto the arc of rotation of such cam wheel when pinion gear 36 rotatesbetween said intermediate position and its said rst extreme position.The second of said recessed portions is indicated by the referencecharacter 51 and extends about the outer periphery of cam wheel 39 adistance slightly less than, but substantially corresponding to the arcof rotation of such cam wheel when pinion gear 36 rotates between saidintermediate position and its said second extreme position. The radiusof recessed portion 49 is intermediate the radius of the outer peripheryof cam wheel 39 and the radius of recessed portion 51. The peripheralextent of recessed portions 49 and 51 and the purposes of such recessedportions will be made more apparent hereinafter in an operationalexample of the apparatus of the invention.

As previously mentioned, gating means or valve 43 is a two-position,four-way valve. Such valve is located intermediate the source of thepressurized uid used for the actuation of fluid motor 32 and is providedto permit or interrupt, as hereinafter discussed, the flow ofpressurized uid to such motor. As also previously mentioned, gatingmeans or valve 47 is a three-position, three-way valve. Such valve isused to control a supply of pressurized fluid for supplemental operationof the previously discussed gating means or valve 27, 4and supplementaloperation of fluid motor 32, as hereinafter discussed.

An additional gating means or valve 52 is also provided, such gatingmeans comprising a two-position, three-way valve which is normallymaintained in a iirst position by a compression spring 53 connectedthereto. Such gating means or valve is shown as an electrical solenoidvalve which is actuated to its second position when the control winding54 thereof is energized, and is returned to its normal position byspring 53 when control winding 54 is again deenergized following aperiod of energization thereof.

A plurality of manually operated electrical switches 56 and 57 providefor the closing of electrical circuits for the energization of thecontrol winding 54 of solenoid valve 52. Such switches may be locatedadjacent or remote from the remainder of the apparatus, as desired.Switches 56 and 57 are of the type which remain in their open or closedposit-ions to which they are manually actuated until a following manualactuation thereof changes them to their opposite positions. A rstenergizing circuit for control winding 54 extends from terminal X of asource of electrical current of suit-able voltage and capacity, over thecontacts of switch 56 in its closed .position and thence through saidcontrol winding to terminal Y of said current source. A secondenergizing circuit for said control winding extends from terminal X ofsaid current source, over the contacts of switch 57 in its closedposition and thence through control winding 54 to terminal Y of saidcurrent source. For purposes of simpliiication of the drawings, saidsource of current is not shown therein.

Gating means or valve 52 is employed to provide control signals tovalves 47, 43 and 277 such control signals being preferably in the formof pressurized iiuid signals. However, it is pointed out that suchvalves or gating means could be electrical solenoid actuated valves andsaid control signals would, of course, then be electrical signals. It isalso pointed out that gating means or valve 52 could be a valve which isactuated by pressurized uid supplied thereto from one or more remotelocations by the actuation of manually operable pressurized fluidcont-rol valves provided at such locations. Furthermore, one or moremanually operated pressurized fluid control valves could obviously besubstituted for valve S2 and its associated electrical control switches56 and 57.

It is believed that the apparatus arrangement shown in the drawing willnow best be understood by reference to the operational examples of theinvention which follow.

For the purpose of describing the operation of the apparatus, it will beassumed that the reciprocative action of pinion gear 36 is through a 180arc of rotation, such 'actuation of the pinion gear being provided bythe reciprocating actuation of pressurized fluid rnotor 32 and theresultant corresponding actuation of rack 34. It will be further assumedthat the intermediate position at which it is at times desired to stopsaid actuation of pinion gear 36 is midway between the two extremepositions of said arc of rotation. It is also pointed out that theapparatus is ilustrated in the drawing in the positions occupied therebywhen pinion gear 36 has been actuated to its extreme clockwise position.

At some point in time following the actuation of pinion gear 36 to itsextreme clockwise position as mentioned above, cam 14 of programmer ortiming device 12 causes its associated cam lobe 17 to momentarilydepress the plunger assembly 22 of valve 19 thereby supplyingpressurized uid through conductor 28 and through restriction 2S, to behereinafter further discussed, to the right hand side, as shown in thedrawing, of gating means or valve 27. Such pressurized fluid actuatesgating means or valve 27 to the position opposite from that illustrationand pressurized fluid is then supplied through valve 43 and throughconductor or conduit 60 to valve 27, and thence through conductor orconduit 29 to the right hand side, as illust-rated in the drawing, ofuid motor 32. The pressurized uid at such time actuates motor 32 to moveits piston rod 33 and, thereby, rack 34 to the left and causecounterclockwise rotation of pinion gear 36. The pressurized uid in theleft hand side of motor 32 flows, at such time, through conductor 31 togating means or valve 27, and thence through conductor 61 to gatingmeans or valve 43 and to a fluid sink 63, or to atmosphere if thepressurized fluid employed is, for example, compressed air. No otheractuation of the apparatus takes place during such operation, except itis pointed out that cams 38 and 39 are correspondingly moved in acounterclockwise direction by said rotation of pinion gear 36.

At some point in time following the above described counterclockwiserota-tion of pinion gear 36, cam 13 of programmer 12 causes itsassocia-ted cam lobe 16 to momentarily depress plunger assembly 21 ofvalve 18 thereby supplying pressurized uid to conductor 24 and throughrestriction 26, to be hereinafter further discussed, to the left handside of gating means or valve 27. Such pressurized fluid reactuatesvalve 27 to the position shown in the drawings to again alternate thesupply of pressurized uid to motor 32. The tiow path for the pressurizedfluid at such time is over conductor or conduit 6), through valve 27 toconductor or conduit 31 and thence to the left hand side of motor 32.Such fluid again actuates t-he piston rod 33 and, thereby, rack 34 tothe right as illustrated. Pinion gear 36 and cams 38 and 39 are therebyrotated in their clockwise directions. The -iuid in the right hand sideof motor 32 at such time ows through conductor or conduit 29 and valve27, and thence through conductor 61 and valve 43 to sink 63 or toatmosphere, as previously mentioned. 1t is thus apparent that, normally,rack 32 and pinion gear 36, comprising the previously mentioned secondmechanism, are actuated in predetermined synchronism with the firstmechanism 10, such rst mechanism con-trolling the programming cycles ofprogrammer 12 or also being controlled by such programmer as the casemay be.

It will now be assumed that it is desired to actuate pinion gear 36 toits aforesaid intermediate position and to stop such device in thatposition. Accordingly, one of the manually actuated switches 56 or 57 isoperated to its circuit closing position and the control Winding 54 ofsolenoid gating means or valve 52 is energized to actuate such valve tothe position opposite from that shown in the drawing. Following suchactuation, pressurized fluid is supplied through such valve to conductoror conduit 65 and thence to conductors or conduits 66, 67 and 68. Ifpinion gear 36 is in either of its extreme positions at such time, nofurther actuation of the apparatus takes piace immediately, since roller46 associated with cam follower 44 bears against a region of the largeouter periphery of cam 39, such as illustrated. However, assuming at thetime of actuation of valve 52 that the apparatus is in the conditionillustrated in the drawing, following the normal actuation of valve 19of programmer 12 to initiate the counterclockwise rotation of piniongea-r 36, roller 46 and cam follower 44 are permitted to move to theright so that such roller contacts the portion 49, of cam wheel 39,having a smaller radius. Gating means or valve 47 is, therefore,actuated at such time, by the pressurized uid supplied to the left handside thereof over conductor 67, to supply the pressurized iluidsu-pplied to conductor or conduit 66 through valve 47 to conductor orconduit 71 and thence to the right hand side of valve 27. However, suchsupply of pressurized uid has no effect at such time since valve 27 haspreviously been actuated to reverse the supply of pressurized uid tomotor 32. Accordingly, pinion gear 36, and cam wheels 38 and 39,continue to move in a counterclockwise direction until the pressurizedfluid supplied to conductor or conduit 68 can actuate valve 43 toterminate the supply and drain of pressurized fluid to and from motor32. Such termination occurs when the recessed portion 48 of cam wheel 38reaches the point where cam follower 41 is permitted to move to theright to move its associated roller 42 into such recess. Pinion gear 36occupies its said intermediate position at such time and saidtermination of pressurized fluid ow to and from motor 32 stops the motorand, thereby, pinion gear 36 in such intermediate position. Subsequentto the stopping of pinion gear 36, programmer 12 continues toperiodically actuate valves 18 and 19, but the pressurized iiuidsupplied by valve 47, to the right hand side of valve 27, preventsactuation of valve 27 when pressurized fluid is supplied, by theactuation of valve 18, to the left hand side of valve 27.

Assuming now, at the time of the aforesaid actuation of Valve 52, thatthe apparatus is in its other extreme condition, that is, opposite tothat illustrated in the drawing, following the normal actuation of valve18 of programmer 12 to initiate the clockwise rotation of pinion gear36, roller 46 and cam foliower 44 are permitted to move to the right sothat such roller contacts the portion 51, of cam wheel 39, having thesmallest radius. Gating means or valve 47 is, therefore, actuated atsuch time, by the pressurized fluid supplied to the left hand sidethereof over conductor 67, to supply the pressurized fluid, supplied toconductor or conduit 66 through valve 47, to conductor or conduit 72 andthence to the left hand side of valve 27. However, such supply ofpressurized fluid has no elect at such time since valve 27 haspreviously been actuated to reverse the supply of pressurized fluid tomotor 32. Accordingly, pinion gear 36 and cam wheels 38 and 39 continueto move in a clockwise direction until the pressurized uid supplied toconductor or conduit 68 can actuate valve 43 to terminate the supply anddrain of pressurized fluid to and from motor 32. Such termination occurswhen the recessed portion 48 of cam wheel 38 reaches the point where camfollower 41 is permitted to move to the right to move its associatedroller 42 into such recess. Pinion gear 36 occupies its saidintermediate position at such time and said termination of pressurizedfluid ow to and from motor 32 stops the motor and, thereby, pinion gear36 in such intermediate position. Subsequent to the stopping of piniongear 36, programmer 12 continues to periodically actuate valves 18 and19, but the pressurized uid supplied by valve 47 to the left hand sideof valve 27 prevents actuation of valve 27 when pressurized fluid issupplied by the actuation ofl valve 19 to the right hand side of valve27 If pinion gear 36 is moving in a counterclockwise direction betweenits first extreme position and its intermediate position when a controlsignal is supplied from valve 52 to conductor or conduits 65, operationof the apparatus similar to that iirst described above occurs, that is,pinion gear 36, and cam wheels 38 and 39, continue to move in acounterclockwise direction until such gear is stopped in itsintermediate position in the manner above described. Similarly, ifpinion gear 36 is moving in a clockwise direction between its secondextreme position and its intermediate position when a control signal issupplied from valve 52 to conductor or conduit 65, operation of theapparatus similar to that secondly described above occurs, that is,pinion gear 36, and cam wheels 38 and 39, continue to move in aclockwise direction until such gear is stopped irl its intermediateposition.

Assuming now that pinion gear 36 is moving in its counterclockwisedirection and is between its intermediate position and its secondextreme position, the following operation occurs upon the supply of acontrol signal, at such time, to conduit 65. It will be noted that, atsuch time, Valve 27 is in the position of supplying pressurized uid tothe right hand side of motor 32 for the counterclockwise actuation ofpinion gear 36. lt is, therefore, necessary to actuate valve 27 toreverse the supply of iiuid to motor 32 and return pinion gear 36clockwise to its intermediate position. Accordingly, the control signalor pressurized fluid supplied to conduit iows through conduit orconductor 67 to actuate valve 47 to supply the pressurized uid, suppliedto conductor 66 from conduit 65, to conduit 72. Cam wheel 39 is in aposition, at such time, to permit the full movement of cam follower 44and said actuation of valve 47. At such time, the pressurized iiuidsupplied to conductor or conduit 72 is, therefore, supplied to the lefthand end of valve 27 to actuate such valve to reverse the connections toconduits 29 and 31, and thereby actuate motor 32 to stop thecounterclockwise rotation of pinion gear 36 and rotate it clockwisetowards its intermediate position. Upon reaching said intermediateposition, the pressurized iluid supplied to conductor or conduit 68 fromconduit 65 operates valve 43, in the manner previously described, toterminate fluid iiow to and from motor 32, and pinion gear 36 stops inits intermediate position.

lf pinion gear 36 is moving in its clockwise direction and is betweenits intermediate and its iirst extreme position, the following operationoccurs upon the supply of a control signal, at such time, to conduit 65.It will be noted that, at such time, valve 27 is in the position ofsupplying pressurized fluid to the left hand side of motor 32 for theclockwise actuation of pinion gear 36. It is, therefore, necessary toactuate valve 27 to reverse the supply of uid to motor 32 and returnpinion gear 36 counterclockwise to its intermediate position.Accordingly, the control signal or pressurized fluid supplied to conduit65 flows through conduit 67 to actuate valve 47 to supply thepressurized iiuid, supplied to conductor 66 from conduit 65, to conduit'71. Cam wheel 39 is in a position, at such time, to permit only partialmovement of cam follower 44 and said actuation of valve 47. At suchtime, the pressurized Huid supplied to conduit 71 is supplied to theright hand end of valve 27 to actuate such valve to reverse theconnections to conduits 29 and 31, and thereby actuate motor 32 to stopthe clockwise rotation of pinion gear 36 and rotate it counterclockwisetoward its intermediate position. Upon pinion gear 36 reaching itsintermediate position, the pressurized uid supplied to conduit 68 fromconduit 65 operates valve 43, in the manner previously described, toterminate fluid flow to and from motor 32. Pinion gear 36 is therebystopped in its intermediate position.

It will he noted that when valve 43 is actuated to terminate iiuid flowto and from motor 32 as described above, such motor will not again beactuated until valve 43 is reactuated to permit the flow of pressurizeduid to motor 32. It is also apparent that the reactuation of motor 32and the lresultant operation of pinion gear 36, following a period ofstopping thereof, should be accomplished so t-hat pinion gear 36 isagain operated in synchronism with the operation of the first mechanism10 which perhaps was permitted to continue its operation during saidperiod of the stopping of motor 32 and pinion gear 36. Accordingly oneend of a conductor or conduit 73 is connected to conductor or conduit 24between restriction 26 and valve 18 of programmer 12, the other end ofconduit 73 being connected to the right hand side of valve 43. When itis desired to again start the operation of motor 32 and the secondmechanism (rack and pinion gear 34-36) following a period of stoppingthereof, the respective manually operated switch 56 or 57 which waspreviously operated to its circuit closing position to cause theactuation of pinion gear 36 to and the stopping thereof in itsintermediate position, is operated to its open position. The winding 54of gating means or valve 52 thus becomes deenergized and compressionspring 53 returns valve 52 to its normal position shown in the drawing.The supply of pressurized fluid to conductor or conduit 65 is therebyinterrupted and such conduit is connected to a fiuid sink 74, or toatmosphere if the pressurized fluid is, for example, compressed air.Such actuation of Valve 52 relieves the pressure supplied to conduits65, 66, 67 and 68, and when valve 18 of programmer 12 is actuated bysuch programmer to supply an impulse signal to conduit 24, such signalis supplied to the left hand side of valve 27 and also, through conduit73, to the right hand side of valve 43. Such signal actuates valve 27 toits position shown in the drawing, if such valve 27 does not alreadyoccupy such position, and also actuates valve 43 to its normal fluid-dowposition shown. Such actuation of valves 27 and 43 permits pressurizedfluid to flow to and from the left and right hand sides, respectively,of motor 32. Motor 32 is thus actuated to cause rotation of pinion gear36 in its clockwise direction again starting its reciprocative operationin synchronism with programmer 12 and first mechanism 10.

It is pointed out at this time that restrictions 25 and 26 are providedto assure operation of valve 27 when pressurized uid is supplied to theright and left hand sides, respectively, of such valve through conduits71 and 72, respectively. Said restrictions, at such times, restrict theflow of duid from conduits 71 and 72 to conduits 28 and 24,respectively. It is also pointed out that, following an actuation ofvalve 47 by a control signal supplied to conduit 67, valve 47 is notreturned to its normal position shown in the drawing until pinion gear36 is actuated to its first extreme position, that is, to the positionat the end of the clockwise rotation of pinion gear 36. At such time camwheel 39 presses against roller 46 and actuates cam follower 44 toreturn valve 47 to its normal position shown in the drawing.

It should also be pointed out that the valves 27, 43, 47 and 52 areshown in the drawings in a conventional manner, and that any suitabletype of valve, such as for example spool type valves, may be used forsuch valves. If spool type valves are employed for valves 43 and 47, thecam followers 41 and 44 may be connected to the spools of the respectivevalves to prevent or permit the actuation of such valves in the mannerhereinbefore described.

Although there is herein shown and described only one form of apparatusfor practicing the invention, it will be understood that various changesand modifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope thereof.

What is claimed is:

1. In a control system in which first and second impulse signals arealternately supplied in synchronism with a first actuated mechanism andthrough first and second conductors, respectively, to a first signalresponsive gating means for alternation of the flow of pressurized fiuidsupplied from a source thereof to a fluid pressure motor connected toreciprocatively actuate a second mechanism between first and secondexereme positions, respectively, in accordance with said alternation andin a timed relationship with said first mechanism; apparatus for attimes actuating said second mechanism to a position intermediate saideXtreme positions and for stopping such mechanism in such intermediateposition, such apparatus comprising, in combination, cam means actuatedin synchronism with said second mechanism, three-position second gatingmeans normally in a first position and at different times actuable inresponse to a control signal to second or third positions; a first camfollower associated with said cam means and said second gating means forpermitting actuation of such gating means to its said second or thirdpositions in response to said control signal according as said secondmechanism is between said intermediate position and said first or saidsecond extreme positions, respectively, and for returning the secondgating means to its said first position when such gating means is inother than such first position and said second mechanism moves into oneof its said eXtreme positions; two-position third gating means normallyin a first position and at times actuable in response to a controlsignal to a second position, said gating means inserted intermediatesaid pressurized fluid source and said uid motor and permitting orinterrupting ow of said fluid according as such gating means is in itssaid first or second positions, respectively; a second cam followerassociated with said cam means and said third gating means forpermitting actuation of such third gating means to its said secondposition in response to said control signal only when said secondmechanism is in its said intermediate position; a manually actuablegating means for supplying when actuated, a control signal to saidsecond and third gating means; means controlled by said second gatingmeans for supplying a control signal to said first gating means throughsaid first or second conductors when said manual gating means isactuated and such second gating means is in its said second or thirdpositions, respectively; and means connecting said rst conductor andsaid third gating means for supplying said first impulse signal to suchthird gating means for reactuating such gating means to its said firstposition when it is in its said second position and said control signalsupplied thereto is terminated.

2. Apparatus, in accordance with claim 1, in which said signals arepressurized fiuid signals and said gating means are fluid ow controlvalves.

3. Apparatus, in accordance with claim 2, in which said pressurizedfluid signals are supplied from a source of compressed air.

4. In a control system in which a fluid pressure motor is connected toreciprocatively operate a second mechanism between first and secondpositions in a timed relationship with a first mechanism in accordancewith first and second impulse signals alternately supplied insynchronism with said rst mechanism to first and second ends of a firstsignal responsive valve for alternation of the flow of pressurized fluidfrom a source thereof to said motor and, thereby alternation of theoperation of such motor; a modification to said control system for attimes actuating said second mechanism to a position intermediate saidrst and second positions and for stopping such mechanism in suchintermediate position, such modification comprising, first and secondcam means operated in synchronism with said second mechanism; a secondcontrol valve normally permitting said ow of pressurized iiuid to saidmotor and controlled by said first cam means so as to be actuable inresponse to a control signal for interrupting such flow only when saidsecond mechanism is in its said intermediate position, a third controlvalve controlled by said second cam means so as to be actuable inresponse to a control signal to supply a control signa-l to said firstor second ends of said first Valve according as said second tive toreactuate the valve only following the termina- 10 tion of said controlsignal.

5. Apparatus, in accordance with claim 4, in which said pressurizedfluid comprises a liquid under pressure.

1 O 6. Apparatus, in accordance with claim 4, in which said signals arepressurized fluid signals.

7. Apparatus, in accordance with claim 6, in which said pressurized uidsignals are compressed air signals.

References Cited UNITED STATES PATENTS 3/1931 Miedbrodt 137-624.126/1949 Olson 91--39 MARTIN P. SCHWADRON, Primary Examiner.

G. N. BAUM, Assistant Examiner.

4. IN A CONTROL SYSTEM IN WHICH A FLUID PRESSURE MOTOR IS CONNECTED TORECIPROCATIVELY OPERATE A SECOND MECHANISM BETWEEN FIRST AND SECONDPOSITIONS IN A TIMED RELATIONSHIP WITH A FIRST MECHANISM IN ACCORDANCEWITH FIRST AND SECOND IMPULSE SIGNALS ALTERNATELY SUPPLIED INSYNCHRONISM WITH SAID FIRST MECHANISM TO FIRST AND SECOND ENDS OF AFIRST SIGNAL RESPONSIVE VALVE FOR ALTERNATION OF THE FLOW OF PRESSURIZEDFLUID FROM A SOURCE THEREOF TO SAID MOTOR AND, THEREBY ALTERNATION OFTHE OPERATION OF SUCH MOTOR; A MODIFICATION TO SAID CONTROL SYSTEM FORAT TIMES ACTUATING SAID SECOND MECHANISM TO A POSITION INTERMEDIATE SAIDFIRST AND SECOND POSITIONS AND FOR STOPPING SUCH MECHANISM IN SUCHINTERMEDIATE POSITION, SUCH MODIFICATION COMPRISING, FIRST AND SECONDCAM MEANS OPERATED BY SYNCHRONISM WITH SAID SECOND MECHANISM; A SECONDCONTROL VALVE NORMALLY PERMITTING SAID FLOW OF PRESSURIZED FLUID TO SAIDMOTOR AND CONTROLLED BY SAID FIRST CAM MEANS SO AS TO BE ACTUABLE INRESPONSE TO A CONTROL SIGNAL FOR INTERRUPTING SUCH FLOW ONLY WHEN SAIDSECOND MECHANISM IS IN ITS SAID INTERMEDIATE POSITION, A THIRD CONTROLVALVE CONTROLLED BY SAID SECOND CAM MEANS SO AS TO BE ACTUABLE INRESPONSE TO A CONTROL SIGNAL TO SUPPLY A CONTROL SIGNAL TO SAID FIRST ORSECOND ENDS OF SAID FIRST VALVE ACCORDING AS SAID SECOND MECHANISM ISBETWEEN SAID INTERMEDIATE POSITION AND SAID FIRST POSITION, OR BETWEENSUCH INTERMEDIATE POSITION AND SAID SECOND POSITION, RESPECTIVELY;MANUAL CONTROL MEANS FOR SUPPLYING SAID CONTROL SIGNALS TO SAID VALVES;AND MEANS FOR SUPPLYING ONE OF SAID IMPLUSE SIGNALS TO SAID SECOND VALVEFOR REACTUATION THEREOF TO AGAIN PERMIT SAID FLUID FLOW TO SAID MOTORFOLLOWING A PERIOD OF INTERRUPTION OF SUCH FLOW BY THE ACTUATION OF SUCHVALVE IN RESPONSE TO A CONTROL SIGNAL, SUCH IMPULSE SIGNAL BEINGEFFECTIVE TO REACTUATE THE VALVE ONLY FOLLOWING THE TERMINATION OF SAIDCONTROL SIGNAL.